1. Field of the Invention
This invention relates to integrated circuits in general and, more particularly, to a system processing unit which can be extended using a plurality of programmable logic units for a plurality of functions.
2. Description of Related Art
The concepts of integrated circuits and computer systems are generally well known. A typical computer system is made up of a multitude of different, specialized computer chips. Chip makers can now place an increasingly large number of transistors on a single chip. For example, currently chip manufacturers are able to place up to ten million transistors on a single integrated circuit or monolithic substrate. It is anticipated that within several years chip makers will be able to place one billion transistors on a single chip. Thus, computer systems are evolving toward comprising a handful of computer chips, where each computer chip comprises a plurality of functions. Economies of scale in manufacturing require that start-up costs be amortized over as many pieces of a product as possible to keep per-unit costs low. Custom integrated circuits are usually only produced in limited numbers, making the per-unit costs much higher than standard integrated circuits. This makes many custom integrated circuits uncompetitive in the marketplace. Therefore, an improved system is desired which allows a variety of custom integrated circuits to be designed and manufactured as a single integrated circuit, so that start-up costs can be amortized over a plurality of different integrated circuit products.